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  • Springer  (218)
  • Cell Press
  • Copernicus
  • American Meteorological Society
  • 2015-2019  (68)
  • 2000-2004  (40)
  • 1990-1994  (83)
  • 1980-1984  (49)
  • 1975-1979  (33)
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  • 1
    Electronic Resource
    Electronic Resource
    Mass mortality of Strongylocentrotus droebachiensis (Echinodermata: Echinoidea) off Nova Scotia, Canada (1984)
    Springer
    Marine biology 78 (1984), S. 153-164 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A mass mortality of Strongylocentrotus droebachiensis, attributed to disease, was monitored in an echinoiddominated barren ground at Eagle Head on the south-western coast of Nova Scotia, Canada, in 1982. Mortality was 70% in a shallow (3 m) nearshore area, resulting in a loss of echinoid biomass of 2 042 g fresh weight m-2, and 6% in deeper (7 m, 10 m) offshore areas. Echinoid density, size and nutritional condition (gonad index) were highest in the nearshore area. Survivorship was higher in juveniles (〈15 mm diameter) than in adults resulting in the formation of a bimodal size distribution in the nearshore area. Mortality began around early October, near the peak of the annual cycle of seawater temperature (∼15°C), and was arrested by early December (seawater temperature ∼7°C) when morbid echinoids appeared to recover. In laboratory experiments, time to morbidity of S. droebachiensis exposed to morbid conspecifics increased exponentially with decreasing temperature (20° to 8°C). There was no survival at 20° and 16°C, 20% survival at 12°C and 100% survival at 8°C after 60 d; suggesting a lower temperature limit (between 12° and 8°C) for possible transmission of a pathogenic agent. Morbid laboratory echinoids from experiments at 16°C, and recovering echinoids collected in the nearshore area in early December, showed 100 and 85% survival respectively at 〈=8°C, and 0 and 15% survival respectively at 16°C, after 30 d. Time to morbidity was not affected significantly by nutritional condition and was similar for juvenile and adult echinoids. Time to morbidity was greater in echinoids exposed to one or three morbid individuals continuously, or seven morbid individuals for 1 h, relative to higher levels of exposure (up to seven morbid individuals continuously). Recent mass mortalities in S. droebachiensis have occurred in years of record high sea surface temperatures. The extent of mortality is correlated with the magnitude and duration of temperatures above a lower limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394695
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  • 2
    Electronic Resource
    Electronic Resource
    Stable carbon isotope variability in marine macrophytes and its implications for food web studies (1984)
    Springer
    Marine biology 81 (1984), S. 223-230 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stable carbon isotope ratios (δ13C) of eelgrass Zostera marina and of kelp Laminaria longicruris showed considerable variation in time and space. The isotopic composition of Z. marina varied seasonally from a mean of-6‰ for leaves formed in June to a mean of-10‰ for leaves formed in February. The maximum range for individual leaves was from-5 to-11.4‰. Once a leaf was fully formed, its isotopic composition appeared not to change. In L. longicruris there was no clear seasonal pattern of variation, but in any given blade there was a spatial pattern of variation, with the thickened central band tending to be least negative and the margins most negative. In one blade the range was from-12 to-20‰. Since this range overlaps values that are found in various other macrophytes and in seston, the value of the stable carbon isotope ratio as a tracer in food webs involving macroalgae is questioned. For Z. marina, in which the values are seasonally predictable, the technique may be useful if interpreted with care. The most probable explanation of variation in the ratios is differential storage of biochemical components of different isotopic compostion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393216
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  • 3
    Electronic Resource
    Electronic Resource
    Order of fertilization within the ovary in Phaseolus coccineus L. (Leguminosae) (1991)
    Springer
    Sexual plant reproduction 4 (1991), S. 126-131 
    Details
    ISSN: 1432-2145
    Keywords: Phaseolus coccineus ; Pollen vigor ; Seed maturation ; Ovule fertilization ; Seed abortion ; Order of fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Phaseolus coccineus typically has six linearly arranged ovules per ovary. The three ovules near the stylar end of the fruit (positions one, two, and three) are more likely to produce mature seeds, to produce heavier seeds, and to produce more vigorous progeny than the ovules in positions near the peduncular/basal end of the fruit (ovule positions four, five, and six). We conducted a series of field experiments designed to supplement our understanding of the mechanisms determining these position effects. We found that approximately 98% of the ovules in 752 fruits were fertilized — about 0.6% of the stylar ovules were not fertilized, whereas 3.2% of the basal ovules were unfertilized. Moreover, we found that only about 49% of the ovules in these 752 fruits produced mature seeds. Over 60% of the stylar ovules produced mature seeds, whereas only 37% of the basal ovules produced mature seeds. Consequently, the proportion of fertilized ovules cannot explain the differences in seed maturation among the ovule positions. We found that after 6.5 h most of the fertilized ovules were located in the stylar ovule positions, and that there were no fertilized ovules in ovule positions five and six, indicating that the stylar ovules are fertilized first. When only the fastest growing pollen tubes were permitted to enter the ovary (due to exision of the style), only the ovules at the stylar end were fertilized, indicating that the ovule positions that are fertilized first are indeed fertilized by the fastest growing pollen tubes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196499
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of genotype on pollen performance in Cucurbita pepo (1991)
    Springer
    Sexual plant reproduction 4 (1991), S. 208-214 
    Details
    ISSN: 1432-2145
    Keywords: Cucurbita pepo ; Pollen competition ; Geno-type ; Non-random fertilization ; Pollen performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study examines the assumption of the pollen competition hypothesis that genetic differences among microgametophytes lead to differences in pollen performance and result in non-random fertilization. In addition, we examined the assumption that pollen performance is genetically correlated with sporophyte vigor due to an overlap in gene expression between the two stages of the life cycle. The results from a pollen mixture experiment in which two cultivars of common zucchini were used show that the ability to sire seeds is nonrandom with respect to the cultivar of the pollen donor plant. The proportion of the progeny sired by the two cultivars is not independent of the region of the fruit where the seeds are produced. The progeny sired by the yellow cultivar outperformed the progeny sired by the green cultivar in a greenhouse study. In addition, the progeny sired by the yellow cultivar from the stylar region of the fruit germinated faster and had more leaf area than the progeny sired by the same cultivar from the peduncular end of the fruit. Thus, the most vigorous progeny are obtained from the stylar region of the fruit where the ovules are fertilized by the most vigorous microgametophytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00190007
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of soil phosphorus on pollen production, pollen size, pollen phosphorus content, and the ability to sire seeds in Cucurbita pepo (Cucurbitaceae) (1994)
    Springer
    Sexual plant reproduction 7 (1994), S. 215-220 
    Details
    ISSN: 1432-2145
    Keywords: Pollen ; microgametophyte ; soil phosphorus ; pollen competition ; pollen performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To determine the effects of soil phosphorus on pollen production, pollen grain size, phosphate concentration per pollen grain, and the siring ability of pollen, two cultivars of the common zucchini (Cucurbita pepo) were grown under two soil phosphorus conditions in an experimental garden. Overall, soil phosphorus availability had a significant effect on reproductive output through the female function and on traits affecting the male function of plants (staminate flower production, pollen production per flower, and pollen grain size). In addition, pollen produced by plants in the high phosphorus soils had a higher phosphate concentration than pollen produced by plants in the low phosphorus soils. A pollen mixture experiment revealed that pollen produced by plants in the high phosphorus treatment sired significantly more seeds than pollen produced by plants in the low phosphorus treatment. This study showed that growing conditions such as soil phosphorus can influence the size of a pollen grain and its chemical composition, which, in turn, can affect its ability to sire mature seeds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232740
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  • 6
    Electronic Resource
    Electronic Resource
    Elevated concentrations of mercury in mussels (Mytilus californianus) associated with pinniped colonies (1981)
    Springer
    Marine biology 65 (1981), S. 45-48 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The geographic distribution of mercury concentrations in the California mussel Mytilus californianus, collected from 1977–1978 at 43 sites along the western coastline of the continental United States is marked by consistently elevated levels at two locations. These two sites, which are relatively isolated from anthropogenic inputs and mercuryrich minerals, both contain large pinniped and marine bird populations. The relatively elevated mercury levels measured in the excrement of a pinniped from one of those locales indicate that the concentrated discharge of mercuryrich waste products from the marine ecosystem's top carnivores is contaminating lower trophic levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397066
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  • 7
    Electronic Resource
    Electronic Resource
    A mathematical model of proximal tubule absorption (1979)
    Springer
    The journal of membrane biology 47 (1979), S. 377-399 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A previous model of the mechanisms of flow through epithelia was modified and extended to include hydrostatic and osmotic pressures in the cells and in the peritubular capillaries. The differential equations for flow and concentration in each region of the proximal tubule were derived. The equations were solved numerically by a finite difference method. The principal conclusions are: (i) Cell NaCl concentration remains essentially isotonic over the pressure variations considered; (ii) channel NaCl concentration varies only a few mosmol from isotonicity, and the hydrostatic and osmotic pressure differences across the cell wall are of the same order of magnitude; (iii) both reabsorbate osmolality and pressure-induced flow are relatively insensitive to the geometry of the system; (iv) a strong equilibrating mechanism exists in the sensitivity of the reabsorbate osmolality to luminal osmolality; this mechanism is far more significant than any other parameter change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869745
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  • 8
    Electronic Resource
    Electronic Resource
    Models of coupled salt and water transport across leaky epithelia (1981)
    Springer
    The journal of membrane biology 60 (1981), S. 1-20 
    Details
    ISSN: 1432-1424
    Keywords: isotonic epithelial transport ; lateral intercellular space ; linearized Kedem-Katchalsky equations ; intraepithelial solute polarization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A general formulation is presented for the verification of isotonic transport and for the assignment of a degree of osmotic coupling in any epithelial model. In particular, it is shown that the concentration of the transported fluid in the presence of exactly equal bathing media is, in general, not a sufficient calculation by which to decide the issue of isotonicity of transport. Within this framework, two epithelial models are considered: (1) A nonelectrolyte compartment model of the lateral intercellular space is presented along with its linearization about the condition of zero flux. This latter approximate model is shown to be useful in the estimation of deviation from isotonicity, intraepithelial solute polarization effects, and the capacity to transport water against a gradient. In the case of uphill water transport, some limitations of a model of fixed geometry are indicated and the advantage of modeling a compliant interspace is suggested. (2) A comprehensive model of cell and channel is described which includes the major electrolytes and the possible presence of intraepithelial gradients. The general approach to verification of isotonicity is illustrated for this numerical model. In addition, the insights about parameter dependence gained from the linear compartment model are shown to be applicable to understanding this large simulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870828
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of parentage, prior fruit set and pollen load on fruit and seed production in Campanula americana L (1991)
    Springer
    Oecologia 87 (1991), S. 80-85 
    Details
    ISSN: 1432-1939
    Keywords: Campanula americana ; Parental effects ; Fruit production ; Seed production ; Pollen loads
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We conducted a controlled crossing experiment to examine the effects of maternal and paternal parentage, the size of the pollen load, and prior fruit production on the proportion of flowers that set fruit, seed number per fruit and seed weight in a natural population of Campanula americana. Effects due to the maternal parent were large for all measures of fruit and seed production, while the paternal parent had a significant effect only upon mean seed weight. As the number of prior fruits on the maternal plant increased the probability that a flower would produce a mature fruit, the number of seeds per fruit, and total seed weight per fruit all decreased. We found no effect of the size of the pollen loads used in this study on fruit or seed production. These results are consistent with those of other studies that suggest in natural plant populations maternal effects, especially environmental maternal effects, can have an overwhelming effect on fruit and seed production and on seed characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323783
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  • 10
    Electronic Resource
    Electronic Resource
    A cell culture substrate obtained from heat-fused collagen (1975)
    Springer
    Cellular and molecular life sciences 31 (1975), S. 1473-1474 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Coverslips coated with rat-tail collagen dried at 37°C were placed in a hot-air sterilizing oven at 160°C for 2 h. The resulting transparent sterile film was found to be a useful multipurpose substrate for cell culture and for subsequent histological sectioning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01923250
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